Image intensifiers typically include a photocathode layer or component and an electron multiplier of some type. Generally, the photocathode layer or component converts incoming photons into electrons and the electron multiplier (e.g., a photoelectric component or layer, commonly referred to as a gain layer) generates multiple electrons from electrons received from the photocathode layer or component. Often, the electron multiplier (i.e., a gain layer) utilizes electron impact ionization as a gain mechanism to amplify the electrical response generated by the photocathode layer or component (the electrical response generated in response to incoming photons).
Unfortunately, imagers that rely on electron impact ionization as a gain mechanism often experience performance degradation when electrons move along undesirable paths prior to or subsequent to an impact. For example, if electrons backscatter (reflect or bounce) off an input surface of the electron multiplier, these backscattered electrons may create a halo effect that degrades image quality. Additionally or alternatively, some electrons, including backscattered electrons, may be lost between the photocathode layer or component and the electron multiplier (i.e., if the electrons are absorbed by a structure other than the electron multiplier). Still further, electrons may move laterally within the electron multiplier, thereby degrading the spatial fidelity of the electrons output by the electron multiplier. That is, crosstalk between pixels, or adjacent regions, in the photoelectric component or layer may cause performance degradation.
Over time, various solutions have attempted to address at least some of these issues; however, the solutions often fail to address all three of the aforementioned issues. Moreover, the solutions may be inefficient to implement, in terms of time, resources, and cost, especially for a Micro-Electro-Mechanical-Systems (MEMS) image intensifier. For example, some electron multipliers include a collimator grid that reduces halo effect, but the collimator grid may fail to limit crosstalk between pixels of the electron multiplier and increase the amount of electrons lost between the photocathode layer and the electron multiplier. Moreover, adding a collimator grid to a substrate may be expensive and inefficient. Alternatively, some electron multipliers include textured regions while other electron multipliers include doped regions. These doped or textured regions might reduce crosstalk or halo effect, respectively, but neither of these regions addresses both issues (e.g., textured regions might reduce halo effect but do not reduce crosstalk while doped regions might reduce crosstalk without impacting halo effect). In view of the aforementioned issues, an electron multiplier that reduces the halo effect caused by backscattered electrons and reduces crosstalk between pixels, while also limiting the number of electrons lost between the photocathode layer or component and the electron multiplier is desired. In particular, an electron multiplier that provides these advantages for MEMS image intensifiers is desired.